Project Summary/Abstract In recent years, the movement to promote the legalization of medical cannabis has grown in the United States and now 29 States and the District of Columbia have provisions that allow for the use of cannabis for medical reasons. Irrespective of the specific reasons for seeking medical cannabis, adults who have been evaluated for medical cannabis certification report significant sleep-related problems as well as frequent use of cannabis to address their sleep problems. Cannabis use for sleep is a key potential target for interventions given that prior research has found that, among individuals with cannabis use disorders, poor sleep is a barrier to sustained remission from cannabis use. Cognitive Behavioral Therapy (CBT) for insomnia is highly effective in individuals with insomnia comorbid with other health conditions, including substance use disorders; however, existing efficacy trials have not specifically evaluated its benefit in those who use cannabis for insomnia. The impact of CBT for insomnia on either sleep or cannabis use in medical cannabis users is, therefore, unknown. The objectives of this project are to adapt and tailor a telephone-delivered CBT for insomnia for adults who use medical cannabis (CBTi-CB) and to evaluate the acceptability and feasibility of this intervention. Qualitative and quantitative data will be collected to refine an existing CBTi-CB protocol and conduct a pilot test of the modified intervention in adults who use medical cannabis. Adults seeking certification for medical cannabis will be approached while waiting for their appointment and screened for insomnia as well as cannabis use for sleep. After initial qualitative interviews and beta testing, eligible participants (N = 40) will be randomized to CBTi-CB or Sleep Education Control (SE) condition, delivered over the telephone. Participants will provide self- report data on sleep/insomnia, functioning and cannabis use and objective data on sleep quality will be measured by actigraphy. The study will evaluate changes in self-reported and objectively measured sleep, functioning and frequency/quantity of cannabis use during treatment and over the course of 18-weeks post- baseline. Completion of the study aims will provide all of the elements required for a future fully-powered randomized trial of the longer-term efficacy of CBTi-CB among those with medical cannabis. This line of research would be the first to evaluate a highly effective sleep-focused intervention and determine the effects on sleep-related and non-sleep-related cannabis use in a non-treatment seeking population.